Sound projectors are required in many sonar and underwater research applications. For each application, there is a specification that the sound projector must meet. Some important aspects of the specification are acoustic power within a frequency range, maximum operating depth, cavitation depth, electroacoustic efficiency, shape, weight, and cost.
The acoustic performance of a prior-art sound projector is fixed at the time the projector is designed. If this performance exceeds the specification, the projector will be heavier and larger than it needs to be. Furthermore, if this projector is part of a towed system, the tow body and its handling system should also be larger and stronger, all of which add to purchase and operating costs. On the other hand, if the performance of the projector does not meet the specification, one must either sacrifice a portion of the specification, or embark upon a time-consuming and costly redesign of the projector, if indeed a single projector can be made to meet the specification. The major shortcoming of the prior-art sound projectors in either case is that once built, the performance of an individual projector is fixed.